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cmd/compile: for range loop reading past slice end [1.13 backport] #40500

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gopherbot opened this issue Jul 30, 2020 · 10 comments
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cmd/compile: for range loop reading past slice end [1.13 backport] #40500

gopherbot opened this issue Jul 30, 2020 · 10 comments
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CherryPickApproved Used during the release process for point releases FrozenDueToAge
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Go1.13.16

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@gopherbot
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@randall77 requested issue #40367 to be considered for backport to the next 1.13 minor release.

@gopherbot, please open backport issues for 1.14 and 1.13.
@gopherbot gopherbot added the CherryPickCandidate Used during the release process for point releases label Jul 30, 2020
@gopherbot gopherbot mentioned this issue Jul 30, 2020
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@gopherbot gopherbot added this to the Go1.13.15 milestone Jul 30, 2020
@randall77
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This is a rare but serious miscompilation, where loop end conditions aren't respected.

@gopherbot
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Change https://golang.org/cl/245957 mentions this issue: [release-branch.go1.13] cmd/compile: don't addLocalInductiveFacts if there is no direct edge from if block to phi block

@cagedmantis cagedmantis added the CherryPickApproved Used during the release process for point releases label Jul 30, 2020
@gopherbot gopherbot removed the CherryPickCandidate Used during the release process for point releases label Jul 30, 2020
@cagedmantis
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This has been approved since it is a serious issue without any known workarounds.

@BLasan
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BLasan commented Aug 1, 2020

Is this still opened ? @gopherbot

@ianlancetaylor
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@BLasan This issue is still open because the change has not been submitted.

@BLasan
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BLasan commented Aug 2, 2020

@ianlancetaylor /assign me

@BLasan
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BLasan commented Aug 2, 2020

@BLasan This issue is still open because the change has not been submitted.

Can I work on this?

@randall77
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@BLasan Sorry, there's nothing left to do on this particular issue. All that needs to happen is to merge CL 245957 into the release branch. Whoever packages up the next 1.13 point release will do that.

The actual work for making inductive variable detection better is #40502 . There's already one CL for that, but if you're interested in the prove code there might be other improvements to be had. Or look at other prove improvement issues.

@BLasan
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BLasan commented Aug 2, 2020

@BLasan Sorry, there's nothing left to do on this particular issue. All that needs to happen is to merge CL 245957 into the release branch. Whoever packages up the next 1.13 point release will do that.

The actual work for making inductive variable detection better is #40502 . There's already one CL for that, but if you're interested in the prove code there might be other improvements to be had. Or look at other prove improvement issues.

Thanks for the update. I'll pickup a issue from the link you provide

gopherbot pushed a commit that referenced this issue Aug 3, 2020
@randall77 @cagedmantis
[release-branch.go1.13] cmd/compile: don't addLocalInductiveFacts if …
5ebdfd9 
…there is no direct edge from if block to phi block

Currently in addLocalInductiveFacts, we only check whether
direct edge from if block to phi block exists. If not, the
following logic will treat the phi block as the first successor,
which is wrong.

This patch makes prove pass more conservative, so we disable
some cases in test/prove.go. We will do some optimization in
the following CL and enable these cases then.

Fixes #40500.

Change-Id: I27cf0248f3a82312a6f7dabe11c79a1a34cf5412
Reviewed-on: https://go-review.googlesource.com/c/go/+/244579
Reviewed-by: Zach Jones <zachj1@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/245957
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
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Closed by merging 5ebdfd9 to release-branch.go1.13.

@toothrot toothrot modified the milestones: Go1.13.15, Go1.13.16 Aug 6, 2020
@golang golang locked and limited conversation to collaborators Aug 6, 2021
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